Here's the substance on 'Phantom' bash

NEW YORK — The cast couldn't stop singing each other's praises at the premiere of The Phantom of the Opera Sunday night.

Amid all the smiles, the phantom himself, Gerard Butler, gave his co-star Patrick Wilson a friendly jab.

Call it life imitating art. In the big-screen adaptation of the classic musical, opening Dec. 22 in select cities, the two play adversaries competing for the love of innocent ingénue Christine (Emmy Rossum), a songbird at a Paris theater.

Wilson, best known for portraying a tortured gay Mormon in the Emmy-winning miniseries Angels in America, relished being a "dynamic, swashbuckling hero."

He had it easier than Butler, who had to wear a mask in the film and had to learn how to sing. The mask was the more troublesome of the two.

"Some days I would be sweaty, and then the mask would start to sweat," Butler said. "And other days not at all, and the mask would literally stick to my face.

"I had a lot of bruising. The mask was a whole character itself."

The vocal calisthenics were a challenge, too.

"I'd never had a singing lesson in my life," Butler said. "I took hundreds and hundreds and hundreds before this movie. I had a voice, but I never knew I could sing this. I was shocked."

Rossum, meanwhile, put her musical prowess to work in the big-screen spectacle. The actress happens to be a classically trained singer who has performed at the Metropolitan Opera at Lincoln Center.

But thanks to the elaborate period costumes, she said, she had her own difficulties during the shoot.

"The corset! I couldn't eat for 12 hours during the day. I had to eat ice cream! It melted on the way down," said Rossum, who last was seen in The Day After Tomorrow.

If you haven't heard of Rossum yet, you will, says Andrew Lloyd Webber, who brought Phantom to the stage and produced the film. "She sings wonderfully. She looks gorgeous," he said.